This photograph of a father holding his son in the shower has been shared tens of thousands of times on Facebook in the last fortnight. But over the same period it's also also been taken down by the social media platform more than once before ultimately being reinstated each time. Why?

In some ways the picture appears to show a fairly everyday scene. A dad cradling his severely sick child in his arms. Except in this instance, they are in the shower and both naked. The picture was posted on social media by the photographer Heather Whitten who lives in Arizona in the US. It shows her son Fox and her husband, the boy's father Thomas Whitten.

For many viewers the image is a touching portrait of parental care and affection. The reason that father and son were naked was because Fox had Salmonella poisoning for which he would soon after be hospitalised.

"Thomas had spent hours in the shower with him, trying to keep his fever down and letting the vomit and diarrhea rinse off of them both as it came," Whitten wrote in her post accompanying the photo.

"He was so patient and so loving and so strong with our tiny son in his lap... I stepped out and grabbed my camera and came back to snap a few images of it and, of course shared them."

But for some people the image is inappropriate at best and at worst has undertones of paedophilia. Whitten has been surprised by this reaction and was shocked when people posted negative comments about what was for her a beautiful moment.

"There is nothing sexual or exploitative about this image," she wrote in the initial post. "I was taken aback by how many people missed the story or didn't even look past the nudity to find the story."

Controversy about what images of naked children are acceptable is not new. In 1995, before the use of digital cameras was widespread, newsreader Julia Somerville and her husband were questioned by police after they took family photographs of her seven-year-old daughter to be developed at a chemists. Ms Somerville protested that the images were "innocent family photos" and no charges were brought.

In 2001, artist Tierney Gearon's exhibition featuring photos of her naked children at the Saatchi Gallery sparked a row. She later admitted being "completely taken aback" by the reaction to the photos which she described as "kids in masks doing a silly pose".

In photos where a child appears naked with an adult there are additional complications and there may be evidence of something of a double standard. A nude man may appear more sinister to some than a woman without clothes.

Last month, an Australian woman Kelli Bannister posted a photograph - in a similar pose to Whitten's photo - cradling her daughter Summer. It was taken by her five-year-old son on a mobile phone. The reaction to that image was overwhelmingly positive.

Image copyrightKelli Bannister

Whitten told BBC Trending she has been "blown away" by the response to her image, which was actually taken in November 2014. "I wasn't prepared at all," she says. "I was very intimidated by it."

"A disgusting lack of boundaries," posted one person who was less keen on the content.

Whitten told Trending that she respects people's rights to disagree and she has never deleted a negative comment posted under the photo. "But people shouldn't be able to dictate what is right or wrong for other people," she added.

Whitten says some people also contacted her saying it triggered memories of past abuse, something she had not even considered when posting the picture.

But the majority of the comments have been positive. "All I see is a loving caring dad comforting his sick child," reads one. "This is a beautiful image," says another.

And in an online poll run by the Telegraph newspaper 94% of the more than 7,000 people who responded indicated they didn't think the photo was inappropriate.

Despite this, Whitten says the picture has been removed a number of times since being posted on Facebook at the start of May.

A spokeswoman for Facebook confirmed that the picture had been taken down in error but has been reinstated.

Whitten used the hashtag #standupstripdown which empowers photographers to take a stand against social network sites banning photos and the damage that can be done by that, especially for professionals.

Whitten is adamant that the image captures something honest and human. "For me it's just such a positive image and my hope is that it's a normalising image, normalising family nudity," she says.